Protective envelopes for an operator device having a touchscreen can completely enclose the operator device in order to protect the operator device from splashing water. In some embodiments, a protection cover includes a thin diaphragm through which the touchscreen is operated. Furthermore, a protective envelope can be pulled over a monitor in order to enable an operation of the monitor in a sterile area. However, the operator device is not protected from damage caused by falling down. Furthermore, the protective cover needs to be sterilized in an elaborate manner and, when using the protective cover, which can be used as a one-way article, the protective cover can slip out of position so that the operation of the touchscreen in an undisturbed manner is not ensured. The protective envelope needs to have an orifice through which the operator device can be introduced and that needs to be closable in a manner that protects the operator device from splashing water.